iso as an exposure variable - not.

[timbearden]

I understand what you are coming at (sorta), however you still have to consider ISO regardless of the presumption. If you have a camera that can shoot from ISO 100-800, and all have very minimal grain throughout, then doubling the ISO can effect exposure just as the shutter. With that said, if you are wide open on your aperture, and still need more light, and you already have a long exposure, then ISO remains as the only alternative to increasing the exposure.

Ironically when in terms of exposure, ISO and shutter speed are two things I think of first. Aperture, as you mentioned not only deals with exposure, but depth of field. Solely, for purposes of exposure I would look to to ISO and shutter first. Just because people don't always consider their ISO as often as they should, doesn't mean it has nothing do with exposure or has little importance.

If you change any one of the three, there will be a change of exposure.

You also mentioned that if one is to change an exposure in shutter priority than one should consider aperture more so. Why not equally? If you are shooting a landscape, and you wish everything to be in focus, then changing the aperture would effect that. That indeed could change the mood of the photo, and the intent you are trying to convey. With today's cameras, changing the ISO is very beneficial as there will not be a dramatic effect in noise until you get above 1000.

This conversation probably will end with no one really agreeing, but ultimately ISO is very important to exposure and for someone who might read this thread in the future needs to realize how important it is. I'm sure Ansel Adams would be rolling in the grave if he thought he didn't have to consider ISO when using the Zone System in figuring out his exposure.

I digress, tomorrow I'll take photos with my pinhole lens just because the only thing I can do to change the exposure is ISO and shutter. DUN DUN DUN

 

[Buckster]

Funny, my old film camera has a control for setting the ISO.

Yes, and as I remember, you inserted a film with a fixed ASA/ISO value, and could not change that while using that film?

That has not always been the case, once the film was loaded you then only had aperture and shutter speed as 'on camera' controls

Two words: Film backs.

Photographers who wanted that control had it, and could change out film to a different ASA/ISO in the middle of a roll quickly and without a problem using film backs. They could switch between any number of different films on the fly that way.

Even those shooting without bodies that used interchangeable film backs, especially those using 35mm, often loaded and carried multiple cameras with different film speeds to deal with the need for different ASA/ISO on the fly.

The OP's opening statement is a load of rubbish.

 

[inTempus]

I feel the same way about shutter speed. Totally pointless to adjust if you're a pro. The aperture is all that's important. The little button that illuminates the top LCD is more useful than the shutter.

 

[table1349]

What a bunch of horse apples! If you are not shooting full time with the sunny 16 rule settings (ISO 100, f16, 1/125th) you are just a piker with a camera.:mrgreen:

 

[Overread]

Critiques to photographic submissions very often advance advice on lighting, aperture, white balance and also shutter speed. However we very seldom see ' ... nice job with your selection of iso, well done!'

Generally speaking when people critique they look for an talk about the downsides a little more than the upsides (depending of course upon the photo in question). I've certainly in the past both given a recived comments on the ISO - or in most cases the noise - in a shot. It's a little less seen on websizes because resizing hides a lot of nose so its only on the very high or poor exposures that one tends to see it come to light.

When someone asks about exposure control in shutter priority mode the answer is not only to vary the iso as has been promulgated in some recent threads. To say "... when in tV mode iso controls your exposure" is in my opinion an incomplete answer. Variation of the aperture is very much a valid option, probably more so.

Not sure how this adds any case for or against your argument - beginners make mistakes and sometimes people oversimplify comments when talking to others. You might notice this more on TPF at present as we have a lot of new beginners and comparatively speaking fewer advanced photographers talking.

However, within the context of on camera controls, I still believe that the variance of iso away from the sensor's base value is mostly undertaken only when the combination of aperture and shutter speed will not enable us to create the image we want.

True within limits - I've known people (macro photographers within the areas I look at) who will raise the ISO when shooting. Their aperture is fixed and their shutter speed is fast to ensure no blur and a deep depth of field - whilst flash light further aids to preventing motion blur and also adds to the shots light needs to keep the aperture and shutter speed at the desired levels. However raising the ISO specifically in this case results in less flash light dominating the scene -thus meaning that more natural light is allowed to take dominance.
This thus reduces the black/dark backgrounds that often come with macro photography where flash is the dominant light source.

I am sure there are other situations where a specific raising of the ISO is a desired effect that the photographer wants.


However it still does not diminish the fact that the ISO is still playing a key part in the exposure.

 

[Derrel]

Shifting the ISO is really pretty useful in a lot of flash photography situations, especially when your flash units are "maxed out", but you still want more exposure. A couple months ago a friend asked me to come over and help him with a small product shoot, and we did a pretty fair amount of exposure bracketing using the camera's ISO control.

ANother place where ISO value adjustment can be handy is when using a flash that is NOT connected to the camera directly; it is possible to use the flash's ISO setting to deliberately cause, typically, under-exposure for fill-in flash, by deliberately setting the flash unit's ISO control one,two, or even almost three f/stops HIGHER; in this way, deliberate mis-setting of the flash unit's ISO control will cause the flash to output less light than it normally would if the ISO value in use in the camera had been entered correctly. THis mighty seem rather old-school,and it is, but it's the way many people shot fill-in flash photos back in the day using the semi-automatic flash units of the 1970's and 1980's; the camera would be loaded with color film of ISO 100 speed; the flash unit could be set with its ISO value deliberately set to around ISO 640, thus providing fill-in flash that was two and two-thirds EV value dimmer than the exposure of the main,daylight exposure.

I know this second example is not quite what the OP was about, but it does point to an actual method of using the ISO Value setting of photographic equipment as a way to "regulate" exposure.

 

[bentcountershaft]

If I'm shooting a concert with a lot of variance in lighting the ISO is generally the only thing I adjust through the night once I had a shutter speed and aperture I'm happy with. Same thing with out door shots with varying cloud cover.

 

[Hardrock]

Have to totally disagree with the op, ISO is an exposure variable for sure. In order to get F2.8 with 1/400th of a sec at a nighttime football game you have to adjust ISO accordingly. I never had the luxury of buying film but Im sure the people who did would ask for a certain film ie: 100,200,800 for what they were shooting. Im sure they just didnt go to the store and take what ever the person behind the counter gave them. So Im not totally sure what the op is trying to say?!?

 

[Derrel]

I hate to appear to be piling on, but Nikon and Pentax both have very advanced exposure control systems that feature an AUTO ISO. Nikon has a feature called AUTO ISO in wide deployment...it shifts the ISO values up or down as away to maintain a desired exposure setting baseline that the user selects...or to get 'the right exposure' by wildly shifting the ISO used in extreme situations that are far, far outside the normal.

Nikon auto-iso is extremely useful | Community Matters

Nikon D3 / D300 Vs. Canon
"Possibly the most advantageous feature for me that the Nikon D300 and D3 have, and most current Canon models do not, is auto ISO capability. The way Nikon implements it is to allow the user to set the lowest ISO that he or she wishes to use, and also the highest. The lowest shutter speed for the camera to automatically use also may be preset.

From then on the camera, whether set to Aperture Priority, Manual, or full Program mode,the camera will adjust the exposure parameters as usual, but, when the light level falls so low that the camera's minimum lens aperture is reached, and the shutter speed is as low as you have set it to go, the camera will then automatically increase the ISO as much as needed to fall within these parameters. The ISO being set is always visible on the top LCD as well as in the viewfinder.

Here's an example of the power of this feature. Imagine that you're walking down the street on a sunny day photographing people in the shade as well as bright sun. The camera is set to ISO 200, an appropriate sensitivity setting for the situation.

All of sudden you look into the dark doorway of a building and see something worth photography. Maybe it's a simple still life tableau, or possible a murder under way, (Pulitzer prize here I come). With the Nikon you simply frame and shoot. If the camera needs to run the ISO up to 1600 or 6400, whatever is needed to give a usable exposure, you've got the shot. With the Canon and no auto-ISO, you need to take the time to judge what ISO setting might be required, to set it, and then to take the shot. Auto ISO is available on both the D300 and D3."

 

[RSPhotography]

When you shoot with film you make a decision on what ISO film you use. If you're shooting at a concert where you know it will be dark you choose a faster film.

Just because you make the decision early on, doesn't mean that it's not an important part.

The fact you can do it 'on the fly' with a digital SLR is just a convenience.

 

[edouble]

I hate to appear to be piling on, but Nikon and Pentax both have very advanced exposure control systems that feature an AUTO ISO. Nikon has a feature called AUTO ISO in wide deployment...it shifts the ISO values up or down as away to maintain a desired exposure setting baseline that the user selects...or to get 'the right exposure' by wildly shifting the ISO used in extreme situations that are far, far outside the normal.

Nikon auto-iso is extremely useful | Community Matters

Nikon D3 / D300 Vs. Canon
"Possibly the most advantageous feature for me that the Nikon D300 and D3 have, and most current Canon models do not, is auto ISO capability. The way Nikon implements it is to allow the user to set the lowest ISO that he or she wishes to use, and also the highest. The lowest shutter speed for the camera to automatically use also may be preset.

From then on the camera, whether set to Aperture Priority, Manual, or full Program mode,the camera will adjust the exposure parameters as usual, but, when the light level falls so low that the camera's minimum lens aperture is reached, and the shutter speed is as low as you have set it to go, the camera will then automatically increase the ISO as much as needed to fall within these parameters. The ISO being set is always visible on the top LCD as well as in the viewfinder.

Here's an example of the power of this feature. Imagine that you're walking down the street on a sunny day photographing people in the shade as well as bright sun. The camera is set to ISO 200, an appropriate sensitivity setting for the situation.

All of sudden you look into the dark doorway of a building and see something worth photography. Maybe it's a simple still life tableau, or possible a murder under way, (Pulitzer prize here I come). With the Nikon you simply frame and shoot. If the camera needs to run the ISO up to 1600 or 6400, whatever is needed to give a usable exposure, you've got the shot. With the Canon and no auto-ISO, you need to take the time to judge what ISO setting might be required, to set it, and then to take the shot. Auto ISO is available on both the D300 and D3."

My D5000 has auto ISO but I never use it. Like you explained set the parameters for the auto ISO to use and shoot. I prefer to make these decisions myself.

I agree that ISO is just as important as aperture and shutter speed but to a degree I understand the op position. Like Ansel Adams said (not a direct quote) everybody has a viewpoint and it is the responsibility of others to disprove/approve it. I believe Ansel Adams and his colleagues already disproved the op position.

 

[Christie Photo]

Not to open a whole new can of worms... (OK. Yes. New can.)

Don't ISO, ASA, DIN... well, don't they ALL refer to EI... that is, EXPOSURE index?

-Pete

 

[Derrel]

Pentax has an interesting option called TAv mode...here's a web page that shows a picture of this mode on the top deck mode dial, along with another exposure mode called Sv or Sensitivity Priority.

In TAV mode, the users selects a FIXED shutter speed and a fixed aperture, and then the camera computes the exposure by adjusting the ISO values upward or downward.

Pentax K10D Review: 5. Operation & Controls: Digital Photography Review

 

[Helen B]

Not to open a whole new can of worms... (OK. Yes. New can.)

Don't ISO, ASA, DIN... well, don't they ALL refer to EI... that is, EXPOSURE index?

-Pete

Yes, indeed. ISO only equals EI when certain conditions are met. Strictly speaking a film only has one ISO (though B&W films can have ISOs varying over a small range, because the developer used in the ISO test is no longer specified but may be chosen by the tester). Everything else is an EI. As an aside, motion picture colour negative films don't have any ISO speed, because there is no relevant ISO standard - they only have EIs.

Best,
Helen

 

[shaunly]

Pentax has an interesting option called TAv mode...here's a web page that shows a picture of this mode on the top deck mode dial, along with another exposure mode called Sv or Sensitivity Priority.

In TAV mode, the users selects a FIXED shutter speed and a fixed aperture, and then the camera computes the exposure by adjusting the ISO values upward or downward.

Pentax K10D Review: 5. Operation & Controls: Digital Photography Review

Nikon has that mode too. Just put it on M then set your shutter speed and f-stop. Then Auto ISO will do the rest.